Milter-greylist

Hello list!

I get messages like this in my sendmail logs.
I'm woundering if someone else have the same problem.

May  3 14:15:36 sm-mta milter-greylist: [ID 818067 mail.debug] smfi_getsymval failed for {if_addr}
May  3 14:26:03 sm-mta milter-greylist: [ID 818067 mail.debug] smfi_getsymval failed for {if_addr}
May  3 14:29:03 sm-mta milter-greylist: [ID 818067 mail.debug] smfi_getsymval failed for {if_addr}

At first, it was just one per day, but now i have them more frequent (as you can see).
I doesn't look that harmful thought. 
The X-Greylist header get a 0.0.0.0 address instead of the real one.

May  3 14:35:39 sm-mta sendmail[27713]: [ID 801593 mail.info] j43CZcXF027713: Milter add: header: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0b5 (sm-mta.vattenfall.se [0.0.0.0]); Tue, 03 May 2005 14:35:39 +0200 (MEST)

Has anyone any tips about this behavor? Is it harmful? 
(it's only coming sometimes, most mails gets the right header information)
How can this be (re)solved?

Re,
/P